Sen. Edward M. Kennedy (D-Mass.) has committed about $800,000 to producing and airing four five-minute television spots in which members of his family, clergymen, friends and acquaintances affirm that the senator is a man of compassion, sympathy and steadfastness in his personal relationships.

The commercials are being broadcast in Massachusetts, where Kennedy, as usual, faces no serious threat in November, as he bids to extend his 20-year Senate career for another term. In that state at least, he enjoys what is in every sense a good name.

The real purpose of the ads was made clear when they were previewed last week for national political reporters in Washington. They are the first step in a concerted effort to bury the "character issue" that plagued Kennedy in his 1980 presidential race.

That issue had its roots in a college test cheating incident at Harvard. It reached a climax 13 years ago at Chappaquiddick, where Kennedy's woman companion drowned in a car he had driven off a bridge. The senator himself said that "overcome by a jumble of emotions, grief, fear, doubt, exhaustion, panic, confusion and shock," his reaction -- and particularly his delay in notifying authorities of the accident -- was "indefensible."

In the 1970s, the character question was fed by reports of persistent womanizing on Kennedy's part and the estrangement from his wife, Joan, that was awkwardly cloaked in their joint appearances during the 1980 race but formalized by a legal separation after that election.

In the 1980 primaries, the campaign organization of President Carter efficiently exploited the character question, with tough TV ads in which supposedly average citizens said of Kennedy, "I just don't trust him. I don't believe him." Kennedy fought back with ads in which his mother and sisters defended his character, but they were crudely made and obviously defensive.

The new ads are slick and powerful, playing off the tragedies of the Kennedy family, from the deaths of his brothers to the cancer that cost his son a leg. They show the senator carrying on his work under emotional burdens "few of us will ever experience."

The narrator who uses that phrase also says that despite the buffetings of fate by which "lesser men would have been rendered useless . . . Ted Kennedy continues to function as a loving father, as head of the entire Kennedy clan, and as one of the country's most effective senators."

The picture the new ads draw of Kennedy is not a fiction. Like other reporters who have covered him, I can cite examples of unpublicized instances in which the senator has gone out of his way to cheer and comfort and sustain friends and strangers who have suffered illness or accidents or problems of their own.

But the mere fact that he is spending three-quarters of a million dollars of contributors' money to try to spike the character question is in itself a measure of the seriousness with which he views it as an obstacle to his undoubted presidential ambitions.

By raising the issue himself, in his walk-away contest with Republican Ray Shamie in Massachusetts, Kennedy almost guarantees it will be raised again, under possibly more testing circumstances, in his next presidential campaign.

If there were any doubts that there are Democrats determined to defeat Kennedy for president, they should be put to rest by Hamilton Jordan's new book, "Crisis: The Last Year of the Carter Presidency."

Jordan, Jimmy Carter's former chief of staff and principal campaign strategist, writes with undisguised scorn of Kennedy. He reprints, in full, a June 25, 1980, memo he gave the president. In it, he laid out no less than six ways in which "Kennedy's sustained and exaggerated attacks" severely damaged Carter's reelection chances.

He describes as "blackmail" a discussion in which Steve Smith, Kennedy's brother-in-law, allegedly linked Kennedy's willingness to campaign for Carter in the general election to Carter's willingness to help Kennedy pay off his primary election debt.

And Jordan quotes Carter as saying of Kennedy, "I don't think he cares about the party or who wins in November. Deep down, I suspect he'd rather see Reagan elected than me."

What we have here, in short, is a whole new version of the character question. Kennedy is portrayed not just as heedless of other individuals but as one who plays rule-or-ruin with the future of his party and his country.

The odds are good that the "character ads" now running in Massachusetts are not the last that Ted Kennedy will have to buy in the next few years.